Bacnet's Client / Server Nature; Network Types - ABB CBXi Series User Manual

BACNET'S CLIENT / SERVER NATURE

BACnet uses a "Client/Server" architecture. BACnet messages are called service requests. A
sends a service request to a
Client.
Example:
A simple device such as a fixed function VAV controller would typically act as Server.
Front-end software running on a PC would act as a
changing set-points.
Notes:
Server devices cannot initiate communication. Higher end embedded controllers generally include both
server and client functionality. This allows them to share information such as outside temperature with
each other or send alarms to a PC.
BACnet currently defines 35 message types that are divided into 5 groups or classes. For example, one
class contains messages for accessing and manipulating the properties of the objects described above.
A common message type is the "
machine to locate the requested property of the requested object and send its value back to the client.
Other classes of services deal with: alarms and events, file uploading and downloading, managing the
operation of remote devices and virtual terminal functions.

NETWORK TYPES

BACnet messages can be carried over the following types of network:
•
Ethernet
•
ARCnet
•
Master-Slave/Token-Passing (MS/TP)
•
Point-to-Point (PTP)
•
LON
•
BACnet/IP
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Server machine that then performs the service and reports the result to the
BACnet
" service request. This message causes the server
ReadProperty
BACnet Networking
Client reading status values from the VAV and
Client machine
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